This invention is primarily applicable to the upgrading of bauxites, bauxitic clays, and aluminum mineral bearing clays. The conventional method used for the upgrading of bauxites; reference American Institute of Mining and Metallurgical Engineers, technical paper by Alcan International; personnel presented at the 1977 Annual Meeting, Atlanta, Ga., Mar. 6-10, 1977; is to first crush the raw material to a specific size, normally three inches, followed by wet screening at 20 mesh Tyler, retaining the plus 20 mesh size fraction as the upgraded bauxite, and the minus 20 mesh portion is rejected as waste. The upgrading in this case is mainly to reduce the silica in the plus 20 mesh product together with some removal of the iron and titanium minerals. The amount rejected as waste is usually a minimum of 40 percent of the original feed material and contains a relatively high percentage of the desirable aluminum bearing minerals which have the chemical analysis of Al.sub.2 O.sub.3.xH.sub.2 O. In the treatment of clays, in which one of the main uses is for the refractory industry, to the knowledge of the inventor, the only major upgrading that is done on a commercial basis is the use of high magnetic intensity separators using steel wool as the magnetic media primarily for the reduction of the iron content of the raw material. Such magnetic separators are of the type manufactured by the Sala Company of Sala, Sweden. In using steel wool as a magnetic media, the product must be reduced in size to essentially minus 10 microns, which is difficult and expensive; otherwise any granular material essentially coarser than 10 microns hangs up in the steel wool and entails large losses of the desirable portion of the raw material. In addition, only small amounts of magnetically susceptible material can be economically removed due to the limited amount of magnetics that can be held by the steel wool or alternately, only small tonnages of material can be treated by such a high-intensity magnetic unit entailing high capital costs per ton of material treated.
In applying my invention to the upgrading of bauxites, and by the use of a number of low cost beneficiation stages, I have been able to use a high intensity magnetic separator of the Jones type which entails the use of no specific type of magnetic media such as steel wool, allowing me to remove large quantities of magnetically susceptible minerals and in particular iron and titanium minerals from the original feed material at a comparatively low cost. Further, if necessary, I use a desliming stage at preferably 2.0 to 10.0 microns, the combination of which upgrades the original bauxite to an appreciably higher grade than was heretofore possible by the elimination of large amounts of the iron and titanium minerals together with silica, resulting in an appreciably higher grade bauxite than was heretofore economically possible together with an appreciable increase in recovery of the desirable Al.sub.2 O.sub.3.xH.sub.2 O minerals, where x is the amount of water chemically combined with the A1.sub.2 O.sub.3.
In the treatment to upgrade clays, I use a number of novel low cost beneficiation steps including the Jones type magnetic separator, to remove a major portion of the iron and titanium minerals with but minor losses of the desirable aluminum bearing minerals, which in this case are normally predominantly Kaolinite, of which the chemical analysis is Al.sub.2 O.sub.3.2SiO.sub.2. 2H.sub.2 O.